| Rheumatoid arthritis(RA) is a chronic,inflammatory and systemic autoimmune disease. In Addition to the participation of T lymphocyte, B lymphocyte is severe activated durning the development and pathogenesis of RA.The autoantibodies in serum such as antikeratin antibody(AKA)and rheumatoid factor(RF) which is the significant identification for autoimmune diseases contribute to the damages of tissues and organics.The autoantibodies combine with reciprocal antigen into antigen antibody complexes,which then activate complement system and trigger a trail of autoimmune responses.Growing investigations suggest that autoantibodies play an important role in the development and pathogenesis of RA.Due to the unclearness etiopathogenisis of RA,there is no satisfactory treatments and strategies for RA at present. Chaenomeles speciosa (sweet) Nakai is one of the valuable traditional herbs used in treatment for RA with a long history in traditional Chinese medicine.Glucosides of Chaenomeles speciosa(GCS),extracted from the fructus of Chaenomeles speciosa,is an active compound. Our previous studies have showed that GCS had preventive and therapetic effects on rats with collagen-induced arthritis (CIA) and adjuvant arthritis(AA).The therapetic effects of GCS on rat with arthritis related to the G-protein coupled signal transduction pathway.Spleen is the most biggest lymphatic organ in which about 60 percent of B lymphocyte. B lymphocyte is the foundation of humoral immunity where antigen is presented and antibody is secreted.Beta 2-adrenergic receptor(β2AR) is an important GPCR in the inflammatory responses,which contributes to the development and growth of RA in the presence of its abnormal expression.The present study show that the effects of GCS on the secondary inflammatory and pathomorphology of spleen in rats with AA.In addition,we assay the autoantibodies in serum and examine the expression ofβ2AR in spleen lymphocytes(S LC).This study designs to investigateβ2AR-AC-cAMP transmembrane signal transduction of SLC and the effect of GCS on downregulating the level of serum antibodies..OBJECTIVEAccording to the changes of paw swelling, histological morphological of spleen and the levels of serum autoantibodies, this study tends to clarify the influences of spleen functions and therapeutic effects of GCS in rats with AA. To further investigate the downregulating effects of GCS on the level of autoantibodies and cAMP of SLC,we examine the expression ofβ2AR of SLC and explore the latent mechanisms of GCS on downregulating the level of serum antibodies by regulating pathway ofβ2AR-AC-cAM P transmembrane signal transduction of SLC. METHODSFreund's complete adjuvant (FCA) was used to induced AA in rats.Rats were divided into six groups and administrated intragastrically with GCS(30,60,120mg·kg-1, d17-d24) after immunization and GTW(40 mg·kg-1,d17-d24) as positive control groups. And for the groups of normal and AA,rats were given an equal volume of vehicle(CMC-Na) at the same time.Secondary paw swelling of AA rats were measured with volume meter; Histopathological change of spleen was observed by light microscope; The level of circulating immune complexes in serum was determined by PEG6000 assay, while the levels of anti- CⅡantibody, and anti-TB antibody in serum were measured by enzyme-linked immunosorbent assay(ELISA), the level of cAMP in SLC was measured by radioimmunoassay,respectively; The expression ofβ2AR on SLC were detected by Western blot and immunohistochemistry analysis.RESUILTS1. The effects of GCS on relieving joints swelling and inflammation of spleens in rats with AA were correlated with its effects on downregulating the levels of serum autoantibodiesIt was found that GCS(60,120mg·kg-1,ig,d17-d24) significantly suppressed secondary hind paw swelling ,polyarthritis index and spleen index,as well as ameliorated arthritic status histological of spleens in rats with AA.GCS(60,120mg·kg-1,ig,d17-d24) significantly downregulated the levels of CIC, anti-CⅡantibody and anti-TB antibody in serum in rats with AA.The correlation analysis demonstrated that the effect of GCS on reliefing the joint swelling of AA rats was correlated intimately with its effect on downregulating the levels of autoantibodies in serum. 2. The effects of GCS on downregulating the levels of serum autoantibodies in rats with AA were correlated with its effects on decreasing the elevated level of cAMP in SLCGCS(60,120mg·kg-1,ig,d17-d24) significantly diminished the level of cAMP in SLC.The correlation analysis demonstrated that the effect of GCS on downregulating the level of cAMP in rats with AA was correlated intimately with its effect on decreasing the level of cAMP in SLC.3. The expression ofβ2AR on SLC in rats with AA and the regulating effects of GCSThe results of Western blot and immunohistochemistry demonstrated that GCS increased the lowered expression ofβ2AR in SLC markly.The results suggested that GCS inhibited the production of autoantibodies by modulatingβ2AR-AC-cAMP transmembrane signal transduction pathway of SLC.CONCLUSIONS1.GCS surpresses the secondary paw swelling and ameliorates the spleen inflammation while accompany with downregulating the autoantibodies in serum.2. GCS diminishes the elevated level of cAMP in SLC,which is one of the most important characteristics of therapetic effects of GCS.3. GCS upregulated the lowered expression ofβ2AR in SLC,which suggested that GCS might prevent rats from the production of autoantibodies by recovering the pathway ofβ2AR-AC-cAMP normal transmembrane signal transduction of SLC.
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